1. Field of the Invention
The present invention relates to an image generating apparatus, and more particularly, it relates to an image generating apparatus comprising a print head.
2. Description of the Background Art
A thermal transfer printer is known as an image generating apparatus comprising a print head. The structure of a print head 100 employed for such a conventional thermal transfer printer is described with reference to FIG. 16.
As shown in FIG. 16, the exemplary conventional print head 100 has a head portion 110 for printing pictures (characters), a rotary arm 120 rotatably supporting the head portion 110 and an ink sheet guide member 130 for guiding an ink sheet 150.
The head portion 110 generates heat, thereby thermally transferring ink from the ink sheet 150 passing through the space between the head portion 110 and a platen roller 140 to a paper 160. The rotary arm 120 includes a heat sink 121, provided on the upper surface of the head portion 110, having a function of radiating the heat from the head portion 110. The heat sink 121 has a thickness D1 (about 3.0 mm) in a direction A shown in FIG. 16. The heat sink 121 of the rotary arm 120 is formed with a threaded hole 121a meshing with a screw 170. The ink sheet guide member 130 having a thickness D2 (about 1.0 mm) in the direction A is arranged on the upper surface of the heat sink 121. This ink sheet guide member 130 has a guide portion 131 for guiding the ink sheet 150 in a carrying direction and a screw receiving hole 132 receiving the screw 170. The ink sheet guide member 130 is mounted on the heat sink 121 by fastening the screw 170 into the threaded hole 121a of the heat sink 121 through a washer 180 and the screw receiving hole 132 of the ink sheet guide member 130. At this time, the screw 170 is fastened into the threaded hole 121a of the heat sink 121 by a depth (screw margin) D3 (about 2.5 mm), whereby the ink sheet guide member 130 is strongly mounted on the heat sink 121 of the rotary arm 120.
If the thickness D1 (about 3.0 mm) of the heat sink 121 is reduced in order to reduce the amount of the material for the heat sink 121 provided with the ink sheet guide member 130 as well as the cost in the print head 100 mounted on the conventional thermal transfer printer shown in FIG. 16, however, the screw margin D3 (about 2.5 mm) of the heat sink 121 to which the screw 170 is fastened is so reduced that it is difficult to strongly mount the ink sheet guide member 130 on the heat sink 121.
On the other hand, a facsimile or a thermal printer is also known in general as an image generating apparatus, comprising a print head, other than the thermal transfer printer.
For example, Japanese Patent Laying-Open No. 7-111558 (1995) or 5-278299 (1993) discloses such an image generating apparatus.
The aforementioned Japanese Patent Laying-Open No. 7-111558 discloses a facsimile having a head spring arranged between a thermal head (print head) and an upper chassis and mounted on the upper chassis with a screw for uniformizing pressing force for pressing the thermal head against a thermal recording paper.
The aforementioned Japanese Patent Laying-Open No. 5-278299 discloses a thermal printer having a pressing member, employed for pressing a thermal head against a paper, mounted on a head supporter provided with the thermal head with a screw through a plate spring. In the thermal printer disclosed in Japanese Patent Laying-Open No. 5-278299, a printing position of the thermal head is controlled by adjusting the amount of fastening the screw fixing the head supporter provided with the thermal head, the plate spring and the pressing member.
In the facsimile disclosed in the aforementioned Japanese Patent Laying-Open No. 7-111558, however, the thickness (screw margin) of the upper chassis to which the screw is fastened is so reduced that it is difficult to strongly mount the head spring on the upper chassis if the upper chassis is thinned in order to reduce the amount of the material for the upper chassis provided with the head spring as well as the cost, similarly to the conventional thermal transfer printer shown in FIG. 16. Also in the thermal printer disclosed in the aforementioned Japanese Patent Laying-Open No. 5-278299, the thickness (screw margin) of the pressing member to which the screw is fastened is so reduced that it is difficult to strongly mount the head supporter on the pressing member if a portion of the pressing member to which the screw is fastened is thinned in order to reduce the amount of the material for the pressing member on which the head supporter is mounted with the screw as well as the cost, similarly to the conventional thermal transfer printer shown in FIG. 16.
In relation to this, there is generally proposed a structure increasing the thickness (screw margin) of a portion of a member to which a screw is fastened in order to strongly mount a prescribed member on the member to which the screw is fastened.
For example, Japanese Patent Laying-Open No. 2000-58151 or Japanese Utility Model Laying-Open No. 61-199877 (1986) discloses an image generating apparatus having such a structure.
The aforementioned Japanese Patent Laying-Open No. 2000-58151 discloses a facsimile machine having a connecting terminal arranged on the upper surface of a mounting seat extending from a chassis and mounted on the mounting seat with a screw. The mounting seat of the chassis of the facsimile machine disclosed in Japanese Patent Laying-Open No. 2000-58151 is formed with a portion, including a threaded hole meshing with the screw, protruding toward the forward end of the screw (opposite to the head of the screw) for increasing the size of a portion (screw margin) to which the screw is fastened.
The aforementioned Japanese Utility Model Laying-Open No. 61-199877 discloses a terminal fitting mounted on a terminal board. In the terminal fitting disclosed in Japanese Utility Model Laying-Open No. 61-199877, a portion, including a threaded hole meshing with a screw, is formed to protrude toward the forward end of the screw (opposite to the head of the screw) for increasing the size of a portion (screw margin) to which the screw is fastened. The screw is fastened into the threaded hole through a lead wire, thereby strongly fixing the lead wire.
In the facsimile machine disclosed in the aforementioned Japanese Patent Laying-Open No. 2000-58151, however, it is difficult to arrange a member such as a precision machine on the forward end of the screw due to the portion, to which the screw is fastened, formed to protrude toward the forward end of the screw. The terminal fitting disclosed in the aforementioned Japanese Utility Model Laying-Open No. 61-199877 also has a problem similar to that of the aforementioned Japanese Patent Laying-Open No. 2000-58151.